For experienced users

Even as an Administrator it can sometimes be tricky to edit the Hosts file in Vista, or in any Windows 7 system that has been upgraded from Vista. Generally the workaround is to open Notepad by right clicking, selecting run as administrator, and then navigating to Windows/System32/ Drivers/ etc/ hosts - editing, and remembering to save as all files, not text (just click on existing Hosts file to replace.) The hosts file ought never to have a file type extension like .tx...